Given:
The number of extra-large jerseys is 10.
The number of large jerseys is 7.
The number of medium jerseys is 5.
Three jerseys to be taken.
To find the probability that randomly grabs 3 medium jerseys:
The probability is,
[tex]\begin{gathered} P(E)=\frac{\text{Number of favourable outcomes}}{\text{Total number of outcomes}} \\ =\frac{^5C_3}{^{22}C_3} \\ =\frac{\frac{5!}{(5-3)!3!}}{\frac{22!}{(22-3)!3!}} \\ =\frac{\frac{5!}{2!3!}}{\frac{22!}{19!3!}} \\ =\frac{5\times4\times3}{22\times21\times20} \\ =\frac{1}{154} \end{gathered}[/tex]Hence, the probability that randomly grabs 3 medium jerseys is,
[tex]\frac{1}{154}[/tex]